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  • C++ best practice: Returning reference vs. object

    - by Mike Crowe
    Hi folks, I'm trying to learn C++, and trying to understand returning objects. I seem to see 2 ways of doing this, and need to understand what is the best practice. Option 1: QList<Weight *> ret; Weight *weight = new Weight(cname, "Weight"); ret.append(weight); ret.append(c); return &ret; Option 2: QList<Weight *> *ret = new QList(); Weight *weight = new Weight(cname, "Weight"); ret->append(weight); ret->append(c); return ret; (of course, I may not understand this yet either). Which way is considered best-practice, and should be followed? TIA Mike

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  • Unhandled exceptions in BackgroundWorker

    - by edg
    My WinForms app uses a number of BackgroundWorker objects to retrieve information from a database. I'm using BackgroundWorker because it allows the UI to remain unblocked during long-running database queries and it simplifies the threading model for me. I'm getting occasional DatabaseExceptions in some of these background threads, and I have witnessed at least one of these exceptions in a worker thread while debugging. I'm fairly confident these exceptions are timeouts which I suppose its reasonable to expect from time to time. My question is about what happens when an unhandled exception occurs in one of these background worker threads. I don't think I can catch an exception in another thread, but can I expect my WorkerCompleted method to be executed? Is there any property or method of the BackgroundWorker I can interrogate for exceptions?

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  • Rendering a variable with erb.

    - by TZer0
    I've got the following problem: I have rhtml (html minced together with ruby inside <% % and <%= % tags) stored in a database which I want to render. The information is acquired through a query. I need to be able to evaluate the information I get from the database as though as it was normal content inside the .erb-file. What I currently have: <% @mymods.each do |mod| %> <%= render_text(mod["html"])%> <% end %> Where mod["html"] is the variable containing the rhtml-code and @mymods an array of objects from the query. I have currently no idea what function I should use (render_text does, of course, not work). Help is greatly appreciated. /TZer0

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  • MVC actionlink posting List of complex type

    - by Ying
    I have an actionlink that on click im passing a List of objects to a controller action. Example: View: Html.ActionLink("TestLink", "TestMethod", "Test", Model.SampleList, null) TestController: public ActionResult TestMethod(List sampleList) { return View(sampleList); } When I do this I get a null sampleList. I can pass a single complex object fine just not a collection of it. Do I need the correct routing for this? The reason I'm doing this is instead of passing an id and do a look up in the controller action, I just pass in the data.

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  • PostgreSQL - disabling constraints

    - by azp74
    I have a table with approx 5 million rows which has a fk constraint referencing the primary key of another table (also approx 5 million rows). I need to delete about 75000 rows from both tables. I know that if I try doing this with the fk constraint enabled it's going to take an unacceptable amount of time. Coming from an Oracle background my first thought was to disable the constraint, do the delete & then reenable the constraint. PostGres appears to let me disable constraint triggers if I am a super user (I'm not, but I am logging in as the user that owns/created the objects) but that doesn't seem to be quite what I want. The other option is to drop the constraint and then reinstate it. I'm worried that rebuilding the constraint is going to take ages given the size of my tables. Any thoughts?

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  • Clipboard Debugging

    - by Jake Pearson
    In the olden times of .NET 1.1, I could use the SoapFormatter to find out exactly what was getting serialized when I copied an object into the clipboard. Fast forward to 2010, and I tried to do the same trick. It turns out the SoapFormatter does not support generics. Is there an alternative way to find out exactly what binary objects are serialized into the clipboard? For example lets say I have this class: public class Foo { public List<Goo> Children; } If I send an instance of it to the clipboard, I would like to take a look at what is in the clipboard to see if it's children list was included or not. Update: I was finally able to find the over copied field with the debugger. Visual Studio did it's job.

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  • Dynamic data validation in ASP.NET MVC

    - by user252160
    I've recently read about the model validation capabilities of ASP.NET MVC which are all very cool until a certain point. What happens if the application doesn't know the data that it works with because it is all stored in DB and built together at runtime. Just like in Drupal, I'd like to be able to define custom types at runtime, and assign runtime validation rules as well. Obviously, the idea of assigning attributes to well established models is now gone. What else could be done ? I am thinking in terms of rules being stored as JSON objects in the DB fields or something like that.

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  • object assignment

    - by sandhya
    Hi i have a scenario like myclass obj1 = new myclass(); ............//some operations on obj1; myclass obj2 = new myclass(); obj2 = obj1; now, my problem is if i modify any parameter, it is effected in both objects (as both refer to same location). but, when i modify obj2 parameter, it should not parameter value in obj1. (means both should not point to same location). how can i do that? please help me

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  • Why use SyncLocks in .NET for simple operations when Interlocked class is available?

    - by rwmnau
    I've been doing simple multi-threading in VB.NET for a while, and have just gotten into my first large multi-threaded project. I've always done everything using the Synclock statement because I didn't think there was a better way. I just learned about the Interlocked Class - it makes it look as though all this: Private SomeInt as Integer Private SomeInt_LockObject as New Object Public Sub IntrementSomeInt Synclock SomeInt_LockObject SomeInt += 1 End Synclock End Sub Can be replaced with a single statement: Interlocked.Increment(SomeInt) This handles all the locking internally and modifies the number. This would be much simpler than writing my own locks for simple operations (longer-running or more complicated operations obviously still need their own locking). Is there a reason why I'd rolling my own locking, using dedicated locking objects, when I can accomplish the same thing using the Interlocked methods?

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  • Bind Data after TCP receive.

    - by gtas
    I have this strange problem all day now. I dunno if you handled something similar. I used two different serializers and now i know its not this problem. Im sending some data over TCP Sockets. Serialize - Send - Deserialize, everything works ok, i can get my objects search through them, use they're properties! But, if e.g receive a BusinessObject[] and convert into List<BusinessObject>, then bind the list in a Control.DataSource = businessObjectList; BOOM! NotSupportedException. Tried it with 3 different controls. Same behaviour. My head is empty of ideas right now!! The Send TCP happens on Desktop Framework, Receive on Compact Framework. But i dont think this has to do with anything. I wish for an explanation on this!

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  • Variable length Blob in hibernate?

    - by Seth
    I have a byte[] member in one of my persistable classes. Normally, I'd just annotate it with @Lob and @Column(name="foo", size=). In this particular case, however, the length of the byte[] can vary a lot (from ~10KB all the way up to ~100MB). If I annotate the column with a size of 128MB, I feel like I'll be wasting a lot of space for the small and mid-sized objects. Is there a variable length blob type I can use? Will hibernate take care of all of this for me behind the scenes without wasting space? What's the best way to go about this? Thanks!

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  • How are java.lang.Object's protected methods protected from subclasses?

    - by Adrian Lang
    The keyword protected grants access to classes in the same package and subclasses (http://java.sun.com/docs/books/tutorial/java/javaOO/accesscontrol.html). Now, every class has java.lang.Object as superclass (http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html). Hence I conclude that every class may access java.lang.Object's methods even if they are protected. Take a look at the following example: public class Testclass { public Object getOne() throws CloneNotSupportedException { return this.clone(); } public Object getTwo() throws CloneNotSupportedException { return ((Object) this).clone(); } } While getOne() compiles fine, getTwo() gives Testclass.java:6: clone() has protected access in java.lang.Object return ((Object) this).clone(); I neither understand why getTwo() doesn't compile nor what's the difference (regarding the access of java.lang.Objects members) with getOne().

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  • What is the "Dispatcher" design pattern?

    - by Ben Farmer
    What is the "dispatcher" pattern and how would I implement it in code? I have a property bag of generic objects and would like to have the retrieval delegated to a generic method. Currently, I have properties looking for a specific key in the bag. For example: private Dictionary<String, Object> Foo { get; set; } private const String WidgetKey = "WIDGETKEY"; public Widget? WidgetItem { get { return Foo.ContainsKey(WidgetKey) ? Foo[WidgetKey] as Widget: null; } set { if (Foo.ContainsKey(WidgetKey)) Foo[WidgetKey] = value; else Foo.Add(WidgetKey, value); } } It was suggested that this could be more generic with the "dispatcher" pattern, but I've been unable to find a good description or example. I'm looking for a more generic way to handle the property bag store/retrieve.

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  • ASP.NET MVC Session usage

    - by Ben
    Currently I am using ViewData or TempData for object persistance in my ASP.NET MVC application. However in a few cases where I am storing objects into ViewData through my base controller class, I am hitting the database on every request (when ViewData["whatever"] == null). It would be good to persist these into something with a longer lifespan, namely session. Similarly in an order processing pipeline, I don't want things like Order to be saved to the database on creation. I would rather populate the object in memory and then when the order gets to a certain state, save it. So it would seem that session is the best place for this? Or would you recommend that in the case of order, to retrieve the order from the database on each request, rather than using session? Thoughts, suggestions appreciated. Thanks Ben

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  • What is the correct way to unit test areas around exceptions

    - by Codek
    Hi, Looking at our code coverage of our unit tests we're quite high. But the last few % is tricky because a lot of them are catching things like database exceptions - which in normal circumstances just dont happen. For example the code prevents fields being too long etc, so the only possible database exceptions are if the DB is broken/down, or if the schema is changed under our feet. So is the only way to Mock the objects such that the exception can be thrown? That seems a little bit pointless. Perhaps it's better to just accept not getting 100% code coverage? Thanks, Dan

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  • Is there a good reflection library available for Scala?

    - by Erik Engbrecht
    I'm working on a library that needs reflection, and needs Scala-specific information as opposed to what is available via the standard Java reflection API. Right now I'm using the undocumented code in scalap (the Scala equivalent to javap) and trying to associate the data it provides with Java reflection objects so that I can call methods and such (scalap just parses class files). I found this but there's nothing there... https://github.com/dubochet/scala-reflection ...and I've searched the Scala SVN repo for traces of it and failed to find it there, either (but it could be I just missed it). Does anyone know of a Scala reflection library that provides information similar to what scalap provides but also allows you to call methods, access fields, etc like the Java reflection library?

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  • C#: Hook up all events from object in single statement.

    - by David
    In my domain layer all domain objects emit events (of type InvalidDomainObjectEventHandler) to indicate invalid state when the IsValid property is called. On an aspx codebehind, I have to manually wire up the events for the domain object like this: _purchaseOrder.AmountIsNull += new DomainObject.InvalidDomainObjectEventHandler(HandleDomainObjectEvent); _purchaseOrder.NoReason += new DomainObject.InvalidDomainObjectEventHandler(HandleDomainObjectEvent); _purchaseOrder.NoSupplier += new DomainObject.InvalidDomainObjectEventHandler(HandleDomainObjectEvent); _purchaseOrder.BothNewAndExistingSupplier += new DomainObject.InvalidDomainObjectEventHandler(HandleDomainObjectEvent); Note that the same method is called in each case since the InvalidDomainobjectEventArgs class contains the message to display. Is there any way I can write a single statement to wire up all events of type InvalidDomainObjectEventHandler in one go? Thanks David

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  • DataBinding and ErrorProvider - How to provide custom error messages?

    - by BeowulfOF
    We use BusinessObjects, implementing IDataErrorInfo and IEditableObject. BindingLists with those Objects are added to BindingSources, those are used to bind UserControls and DataGrids on the forms (WinForms). The BindingSource is additionally set as DataSource to the ErrorProvider of the form. We do use currently TextBoxes for Properties of Type int and short. They are validated inside the BusinessObjects with custom validation, like min/max values, etc. That works fine, since error message form our custom validations show up nicely next to the TextBox. However, if the input is greater than the value of an int (e.g. "9999999999") the BindingSource doesn't even try to enter that Value into the BusinesObject but instead gives the errormessage to the errorprovider like "The value for Int32 was too big.". We do not want to bother our users with "Int32" but want a custom errormessage for that. It is nice, that the BindingSource does provide this feature, but is it possible to provide custom error messages for this?

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  • (MyClassName)object vs. object as MyClassName

    - by Matthew Doyle
    Hello all, I was wondering what is the better method for Casting objects for C#: MyClassName test = (MyClassName)object; MyClassName test = object as MyClassName; I know already that if you do the first way, you get an exception, and the second way it sets test as null. However, I was wondering why do one over the other? I see the first way a lot, but I like how the second way because then I can check for null... If there isn't a 'better way' of doing it, what are the guidelines for using one way or the other?

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  • iPhone: UIImageView not showing images

    - by George
    Hello, I've got UIImageView drawn in my nib-file and it's connected to a imageView iboutlet. I can load single pictures which will show up very nicely, but when it comes to drawing many images separately as like an animation, images won't show. I've got drawImage() function which takes NSData-objects(image data) and draws it to a screen(imageView). Main function has got for loop which loops 300 times as quickly as it can and each time it calls that drawImage function and passes different image data to it. Sometimes when I execute this code, last picture from that "animation" shows up, sometimes not at all. Maybe I need to schedule enough time for imageView so that the image can be shown? Hope someone has some clues. Thanks in advance!

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  • Search object array for matching possible multiple values using different comparison operators

    - by Sparkles
    I have a function to search an array of objects for a matching value using the eq operator, like so: sub find { my ( $self, %params ) = @_; my @entries = @{ $self->{_entries} }; if ( $params{filename} ) { @entries = grep { $_->filename eq $params{filename} } @entries; } if ( $params{date} ) { @entries = grep { $_->date eq $params{date} } @entries; } if ( $params{title} ) { @entries = grep { $_->title eq $params{title} } @entries; } .... I wanted to also be able to pass in a qr quoted variable to use in the comparison instead but the only way I can think of separating the comparisons is using an if/else block, like so: if (lc ref($params{whatever}) eq 'regexp') { #use =~ } else { #use eq } Is there a shorter way of doing it? Because of reasons beyond my control I'm using Perl 5.8.8 so I can't use the smart match operator. TIA

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  • How can I create a MethodInfo from an Action delegate

    - by Michael Meadows
    I am trying to develop an NUnit addin that dynamically adds test methods to a suite from an object that contains a list of Action delegates. The problem is that NUnit appears to be leaning heavily on reflection to get the job done. Consequently, it looks like there's no simple way to add my Actions directly to the suite. I must, instead, add MethodInfo objects. This would normally work, but the Action delegates are anonymous, so I would have to build the types and methods to accomplish this. I need to find an easier way to do this, without resorting to using Emit. Does anyone know how to easily create MethodInfo instances from Action delegates?

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  • Java text classification problem

    - by yox
    Hello, I have a set of Books objects, classs Book is defined as following : Class Book{ String title; ArrayList<tags> taglist; } Where title is the title of the book, example : Javascript for dummies. and taglist is a list of tags for our example : Javascript, jquery, "web dev", .. As I said a have a set of books talking about different things : IT, BIOLOGY, HISTORY, ... Each book has a title and a set of tags describing it.. I have to classify automaticaly those books into separated sets by topic, example : IT BOOKS : Java for dummies Javascript for dummies Learn flash in 30 days C++ programming HISTORY BOOKS : World wars America in 1960 Martin luther king's life BIOLOGY BOOKS : .... Do you guys know a classification algorithm/method to apply for that kind of problems ? A solution is to use an external API to define the category of the text, but the problem here is that books are in different languages : french, spanish, english ..

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  • Help required in adding new methods, properties into existing classes dynamically

    - by Bepenfriends
    Hi All, I am not sure whether it is possible to achieve this kind of implementation in Dot Net. Below are the information Currently we are on an application which is done in COM+, ASP, XSL, XML technologies. It is a multi tier architecture application in which COM+ acts as the BAL. The execution steps for any CRUD operation will be defined using a seperate UI which uses XML to store the information. BAL reads the XML and understands the execution steps which are defined and executes corresponding methods in DLL. Much like EDM we have our custom model (using XML) which determines which property of object is searchable, retrievable etc. Based on this information BAL constructs queries and calls procedures to get the data. In the current application both BAL and DAL are heavily customizable without doing any code change. the results will be transmitted to presentation layer in XML format which constructs the UI based on the data recieved. Now I am creating a migration project which deals with employee information. It is also going to follow the N Tier architecture in which the presentation layer communicates with BAL which connects to DAL to return the Data. Here is the problem, In our existing version we are handling every information as XML in its native form (no converstion of object etc), but in the migration project, Team is really interested in utilizing the OOP model of development where every information which is sent from BAL need to be converted to objects of its respective types (example employeeCollection, Address Collection etc). If we have the static number of data returned from BAL we can have a class which contains those nodes as properties and we can access the same. But in our case the data returned from our BAL need to be customized. How can we handle the customization in presentation layer which is converting the result to an Object. Below is an example of the XML returned <employees> <employee> <firstName>Employee 1 First Name</firstName> <lastName>Employee 1 Last Name</lastName> <addresses> <address> <addressType>1</addressType> <StreetName>Street name1</StreetName> <RegionName>Region name</RegionName> <address> <address> <addressType>2</addressType> <StreetName>Street name2</StreetName> <RegionName>Region name</RegionName> <address> <address> <addressType>3</addressType> <StreetName>Street name3</StreetName> <RegionName>Region name</RegionName> <address> <addresses> </employee> <employee> <firstName>Employee 2 First Name</firstName> <lastName>Employee 2 Last Name</lastName> <addresses> <address> <addressType>1</addressType> <StreetName>Street name1</StreetName> <RegionName>Region name</RegionName> <address> <address> <addressType>2</addressType> <StreetName>Street name2</StreetName> <RegionName>Region name</RegionName> <address> <addresses> </employee> </employees> If these are the only columns then i can write a class which is like public class Address{ public int AddressType {get;set;}; public string StreetName {get;set;}; public string RegionName {get;set;}; } public class Employee{ public string FirstName {get; set;} public string LastName {get; set;} public string AddressCollection {get; set;} } public class EmployeeCollection : List<Employee>{ public bool Add (Employee Data){ .... } } public class AddressCollection : List<Address>{ public bool Add (Address Data){ .... } } This class will be provided to customers and consultants as DLLs. We will not provide the source code for the same. Now when the consultants or customers does customization(example adding country to address and adding passport information object with employee object) they must be able to access those properties in these classes, but without source code they will not be able to do those modifications.which makes the application useless. Is there is any way to acomplish this in DotNet. I thought of using Anonymous classes but, the problem with Anonymous classes are we can not have methods in it. I am not sure how can i fit the collection objects (which will be inturn an anonymous class) Not sure about datagrid / user control binding etc. I also thought of using CODEDom to create classes runtime but not sure about the meory, performance issues. also the classes must be created only once and must use the same till there is another change. Kindly help me out in this problem. Any kind of help meterial/ cryptic code/ links will be helpful.

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  • using core data with web services

    - by Jayshree
    Hi. i am a noob in xcode. I am developing an iphone app where i need to send and receive data from a web service. And i need to store them temporarily in my app. i dont want to use sqlite. so i was wondering if i should use core data for this purpose. I read some articles but i still dont have a clear picture of how to do it, coz i have used core data only with sqlite. I want to do the following things : Will receive table data from a web service. Have to perform certain calculations on those fields. Will send the data back in xml format to the server. How do i convert the xml data into int, date or any other data type? and how do i store it in managed data objects? Can anyone please help me with this??? thnx for your time.

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